I suspect this one is due to none of the sequences being succesfully merged (hence the sequence table is empty and not "valid").
@drmusk can you clarify the primer set you are using? Is it the ~252 nucleotide V4 amplicon region? If it is, when the reads are truncated to 120/120, they won't overlap and none will merge.
Your sequencing data looks to be of good quality, so I would extend your truncation lengths singificantly (e.g. --p-trunc-len-f 220 and --p-trunc-len-r 200) and hopefully your problem will be solved.